The term "silver haloiodide" is employed in its art recognized usage to designate silver halide grains containing silver ions in combination with iodide ions and at least one of chloride and bromide ions. The term "reversal photographic element" designates a photographic element which produces a photographic image for viewing by being imagewise exposed and developed with a first non-chromogenic "black and white" developing agent to produce a negative of the image to be viewed, followed by uniform exposure and/or fogging of residual silver halide and processing to produce a second, viewable image. Such reversal elements are typically sold packaged with instructions to process using a color reversal process such as the Kodak E-6 process as described in The British Journal of Photography Annual of 1988, page 194. Color slides, such as those produced from Kodachrome.RTM. and Ektachrome.RTM. films, constitute a popular example of reversal photographic elements. In the overwhelming majority of applications the first image is negative and the second image is positive. Groet U.S. Pat. No. 4,082,553 illustrates a conventional reversal photographic element containing a silver haloiodide grains modified by the incorporation of a small proportion of fogged silver halide grains. Hayashi et al German OLS No. 3,402,840 is similar to Groet, but describes the imaging silver halide grains in terms of those larger than and smaller than 0.3 micrometer and additionally requires in addition to the fogged silver halide grains or their metal or metal sulfide equivalent an organic compound capable of forming a silver salt of low solubility.
High aspect ratio tabular grain silver haloiodide emulsions have been recognized to provide a variety of photographic advantages, such as improvements in speed-granularity relationships, increased image sharpness, and reduced blue speed of minus blue recording emulsion layers. High aspect ratio tabular grain silver haloiodide emulsions in reversal photographic elements are illustrated by Research Disclosure Vol. 225, January 1983, Item 22534; Wilgus et al U.S. Pat. No. 4,434,226; Kofron et al U.S. Pat. No. 4,439,520; Solberg et al U.S. Pat. No. 4,433,048; Maskasky U.S. Pat. No. 4,400,463; and Maskasky U.S. Pat. No. 4,435,501. Research Disclosure is published by Kenneth Mason Publications, Ltd., The Old Harbourmaster's, 8 North Street, Emsworth, Hampshire P010 7DD, England.
U.S. Pat. No. 4,656,122 describes silver halide photographic elements capable of producing reversal images including one emulsion layer comprising a blend of tabular silver haloiodide grains and fine grains of a silver salt more soluble than silver iodide. The addition of relatively fine grains consisting essentially of a silver salt more soluble than silver iodide to an image forming layer containing tabular silver haloiodide grains may produce a combination of advantages in reversal imaging. The reversal threshold speed of the reversal photographic elements can be increased. At the same time, reduced toe region density in the reversal image as well as increases in maximum density and contrast are observed.
In U.S. Pat. No. 5,391,468, the addition of dye to high solubility fine grains which are added to an imaging emulsion layer is described. No discussion is present of inter or outerlayers. Again, in U.S. Pat. No. 5,176,990, the dual melting of a liquid emulsion to imaging emulsion layers is described.
U.S. Pat. No. 5,552,265 teaches the use of a small amount of fine grains below the bottom layer to add to the Dmin of the red recording. U.S. Pat. No. 4,614,707 also describes the use of Lippmann emulsions and Dox scavengers below the slow layer to sharpen the toe contrast.
The addition of Lippmann emulsions in interlayers to intercept inhibitor has been described in GB 1,201,110 for reversal films and in U.S. Pat. No. 4,752,558 for color negative film.
Imaging dyes used in photographic materials generally have unwanted light absorption which reduce color saturation and may cause loss of color accuracy. Techniques for generating interimage effect (IIE) upon photographic processing are known which will compensate such unwanted light absorption to a certain extent. A recent trend in photographic materials has led to the desire for increased color saturation in various applications. Therefore, techniques for providing more interimage effect would be desirable.
U.S. Pat. No. 5,932,401 discloses a new reversal photographic element film structure which enhances interimage effect by combining a light sensitive imaging emulsion and a relatively large amount of a non-image forming fine grain emulsion in a substantially non-image forming special layer of the element. The use of very fine grain non-image forming emulsions (e.g., preferably less than 0.07 micrometer grain size) is preferred in the special layer to provide a relatively large surface area ratio relative to the imaging emulsion grain surface area to enhance interimage effects. Examples include the use of non-image forming emulsions which do and which do not include iodide.
While interimage effect is increased at all density regions for reversal elements when employing a special layer in accordance with U.S. Pat. No. 5,932,401, it has been found that the effect at mid and high density regions (corresponding to mid and low exposure levels) is enhanced to a greater degree than at low density regions (corresponding to high exposure levels). It would be desirable to further increase the interimage effect over all densities of the image forming element, and in particular in low density regions, to provide higher color saturation in such regions.